Publications by authors named "Shinobu Kohsaka"

13 Publications

  • Page 1 of 1

Long-term follow up of an adult with alternating hemiplegia of childhood and a p.Gly755Ser mutation in the ATP1A3 gene.

Brain Dev 2018 Mar;40(3):226-228

Department of Pediatrics, Hokkaido University Hospital, Sapporo, Japan.

Alternating hemiplegia of childhood (AHC) is a rare neurological disease mainly caused by mutations in the ATP1A3 gene and showing varied clinical severity according to genotype. Patients with a p.Gly755Ser (p.G755S) mutation, one of minor genotypes for AHC, were recently described as having a mild phenotype, although their long-term outcomes are still unclear due to the lack of long-term follow up. Here, we demonstrate the full clinical course of a 43-year-old female AHC patient with p.G755S mutation. Although her motor dysfunction had been relatively mild into her 30 s, she showed a subsequent severe aggravation of symptoms that left her bedridden, concomitant with a recent recurrence of seizure status. The seizures were refractory to anti-epileptic drugs, but administration of flunarizine improved seizures and the paralysis. Our case suggests that the phenotype of AHC with p.G755S mutation is not necessarily mild, despite such a presentation during the patient's younger years.
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http://dx.doi.org/10.1016/j.braindev.2017.11.007DOI Listing
March 2018

Efficacy of perampanel for controlling seizures and improving neurological dysfunction in a patient with dentatorubral-pallidoluysian atrophy (DRPLA).

Epilepsy Behav Case Rep 2017 26;8:44-46. Epub 2017 May 26.

Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.

We administered perampanel (PER) to a bedridden 13-year-old male patient with dentatorubral-pallidoluysian atrophy (DRPLA). The DRPLA diagnosis was based on the presence of a CAG trinucleotide repeat in the gene. The patient experienced continuous myoclonic seizures and weekly generalized tonic-clonic seizures (GTCs). PER stopped the patient's myoclonic seizures and reduced the GTCs to fragmented clonic seizures. The patient recovered his intellectual abilities and began to walk again with assistance. We suggest that PER be considered as one of the key drugs used to treat patients with DRPLA.
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http://dx.doi.org/10.1016/j.ebcr.2017.05.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565628PMC
May 2017

The presence of short and sharp MEG spikes implies focal cortical dysplasia.

Epilepsy Res 2015 Aug 12;114:141-6. Epub 2015 May 12.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, North 15 West 7, Kita-ku, Sapporo, Japan. Electronic address:

Purpose: This study focused on the characteristic needle-like epileptic spikes of short duration and steep shape seen on magnetoencephalography (MEG) in patients diagnosed with focal cortical dysplasia (FCD) morphologically. We aimed to validate the analysis of MEG spike morphology as a noninvasive method of identifying the presence and location of FCD.

Methods: MEG was collected by 204-channel helmet-shaped gradiometers. We analyzed MEG spike sources for 282 patients with symptomatic localization-related epilepsy. MEG showed clustered equivalent current dipoles when superimposed on their three-dimensional-magnetic resonance images (MRI) in 85 patients. Fifty-seven patients were excluded from our study, because they had destructive brain lesions or an insufficient number of spikes for statistical analysis. Twenty-eight patients (18 males, 10 females; aged 1-34 years) were finally matched to our inclusion criteria, and were categorized into three groups: FCD (7 patients), non-FCD (10 patients), and non-lesion (11 patients), based on the MRI findings. We measured the duration, amplitude, and tilt manually for at least 15 spikes per patient, and compared the three groups using a one-way analysis of variance, followed by the Tukey test when statistically significant (p < 0.05). In 17 patients with visible MRI lesions, we investigated the correlation between the depth of the lesion and the tilt using the Pearson product moment correlation.

Results: The average spike duration was significantly shorter in the FCD and non-lesion groups than in the non-FCD group (p < 0.05). The average amplitude was not significantly different between the three groups. The average spike tilt was significantly steeper in the FCD group than in the non-FCD group (p = 0.0058). There was no significant difference between FCD and non-lesion patients in both duration and tilt. Our additional study revealed a significant negative correlation between the depth of the lesion and the average tilt (p = 0.0009).

Significance: MEG epileptiform discharges of short duration and steep tilt characterize FCD, especially when located at the superficial neocortical gyrus. We speculate that this particular spike morphology results from the intrinsic epileptogenicity of FCD. Morphological analysis of MEG spikes can evaluate the etiology of epileptogenic lesions and detect a strong, localized epileptogenic focus such as that typically observed in FCD.
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http://dx.doi.org/10.1016/j.eplepsyres.2015.04.020DOI Listing
August 2015

Advantageous information provided by magnetoencephalography for patients with neocortical epilepsy.

Brain Dev 2015 Feb 10;37(2):237-42. Epub 2014 May 10.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan; Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.

Purpose: We evaluated whether magnetoencephalography (MEG), in addition to surgery, was valuable for the diagnosis and management of epileptic syndromes in patients with neocortical epilepsy (NE).

Methods: We studied MEG in 73 patients (29 females; aged 1-26years; mean 10.3years) for the clinical diagnosis of epilepsy and for preoperative evaluation. MEG data were recorded by 204-channel whole head gradiometers with a 600Hz sampling rate. MEG spike sources were localized on magnetic resonance images (MRI) using a single dipole model to project equivalent current dipoles.

Results: MEG localized an epileptic focus with single clustered dipoles in 24 (33%) of 73 NE patients: 16 (25%) of 64 symptomatic localization-related epilepsy (SLRE) patients and eight (89%) of nine idiopathic localization-related epilepsy (ILRE) patients. MEG provided advantageous information in 12 (50%) of 24 patients with clustered dipoles and confirmed the diagnosis in the remaining 12 (50%). Furthermore, the use of MEG resulted in changes to surgical treatments in nine (38%) patients and in medical management in eight (33%). MEG confirmed the diagnosis in eight (16%) of 49 patients with scattered dipoles. MRI identified a single lesion (28 patients, 38%), multiple lesions (5, 7%), and no lesion (40, 55%). MRI provided confirming information in 19 of 28 patients with a single lesion and 18 of them required surgical resections. MRI did not provide any supportive information in 54 (74%) patients with a single (9), multiple (5) and no lesion (40).

Conclusion: Our study shows that MEG provides fundamental information to aid the choice of diagnostic and therapeutic procedures including changes in medication in addition to surgical treatments for NE.
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http://dx.doi.org/10.1016/j.braindev.2014.04.006DOI Listing
February 2015

Magnetoencephalographic analysis of paroxysmal fast activity in patients with epileptic spasms.

Epilepsy Res 2013 Mar 5;104(1-2):68-77. Epub 2012 Oct 5.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Japan.

Purpose: This study sought to demonstrate the origin and propagation of paroxysmal fast activity (PFA) in patients with epileptic spasms (ESs), using time-frequency analyses of magnetoencephalogram (MEG) PFA recordings.

Methods: A 204-channel helmet-shaped MEG, with a 600Hz sampling rate, was used to examine PFA in 3 children with ESs. We analyzed MEG recordings of PFA by short-time Fourier transform and the aberrant area or high-power spectrum was superimposed onto reconstructed three-dimensional magnetic resonance images as moving images. One ictal discharge was collected. One child and one adult with PFA due to Lennox-Gastaut syndrome were also examined for comparison.

Results: All four PFAs in Patient 1 and five PFAs in Patient 3 were generated from one hemisphere. In Patient 2, four of seven PFAs were generated from one hemisphere and the remaining three were generated from both hemispheres. In Patient 3, one ictal MEG showed ictal discharges that were generated from the same area as the PFA, although the electroencephalogram showed no discharge. In Patients with Lennox-Gastaut syndrome, all 10 PFAs were generated from bilateral hemispheres simultaneously.

Conclusion: Short-time Fourier transform analyses of MEG PFA can show the origin and form of propagation of PFA. These results suggest that ESs are representative of focal seizures and the mechanism of PFA is different between ESs and Lennox-Gastaut syndrome.
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http://dx.doi.org/10.1016/j.eplepsyres.2012.09.001DOI Listing
March 2013

Direct correlation between the facial nerve nucleus and hemifacial seizures associated with a gangliocytoma of the floor of the fourth ventricle: a case report.

Epilepsia 2011 Dec 2;52(12):e204-6. Epub 2011 Nov 2.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan.

A dysplastic neuronal lesion of the floor of the fourth ventricle (DNFFV) causes hemifacial seizures (HFS) from early infancy. However, it is still controversial whether HFS is generated by the facial nerve nucleus or cerebellar cortex. In this study, we confirm a direct correlation between the rhythmic activities in the DNFFV and HFS using intraoperative electroencephalography (EEG) and electromyography (EMG) monitoring. Our results support the theory that a DNFFV provokes ipsilateral HFS via the facial nerve nucleus.
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http://dx.doi.org/10.1111/j.1528-1167.2011.03299.xDOI Listing
December 2011

The applications of time-frequency analyses to ictal magnetoencephalography in neocortical epilepsy.

Epilepsy Res 2010 Aug 1;90(3):199-206. Epub 2010 Jun 1.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.

Purpose: Ictal magenetoencephalographic (MEG) discharges convey significant information about ictal onset and propagation, but there is no established method for analyzing ictal MEG. This study sought to clarify the usefulness of time-frequency analyses using short-time Fourier transform (STFT) for ictal onset and propagation of ictal MEG activity in patients with neocortical epilepsy.

Methods: Four ictal MEG discharges in two patients with perirolandic epilepsy and one with frontal lobe epilepsy (FLE) were evaluated by time-frequency analyses using STFT. Prominent oscillation bands were collected manually and the magnitudes of those specific bands were superimposed on individual 3D-magnetic resonance images.

Results: STFT showed specific rhythmic activities from alpha to beta bands at the magnetological onset in all four ictal MEG records. Those activities were located at the vicinity of interictal spike sources, as estimated by the single dipole method (SDM), and two of the four ictal rhythmic activities promptly propagated to ipsilateral or bilateral cerebral cortices. The patients with FLE and perirolandic epilepsy underwent frontal lobectomy and resection of primary motor area, respectively including the origin of high-magnitude areas of a specific band indicated by STFT, and have been seizure free after the surgery.

Conclusions: STFT for ictal MEG discharges readily demonstrated the ictal onset and propagation. These data were important for decisions on surgical procedure and extent of resection. Ictal MEG analyses using STFT could provide a powerful tool for noninvasive evaluation of ictal onset zone.
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http://dx.doi.org/10.1016/j.eplepsyres.2010.05.001DOI Listing
August 2010

MEG time-frequency analyses for pre- and post-surgical evaluation of patients with epileptic rhythmic fast activity.

Epilepsy Res 2010 Feb 6;88(2-3):100-7. Epub 2009 Nov 6.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan.

Purpose: To evaluate the effectiveness of surgery for epilepsy, we analyzed rhythmic fast activity by magnetoencephalography (MEG) before and after surgery using time-frequency analysis. To assess reliability, the results obtained by pre-surgical MEG and intraoperative electrocorticography were compared.

Methods: Four children with symptomatic localization-related epilepsy caused by circumscribed cortical lesion were examined in the present study using 204-channel helmet-shaped MEG with a sampling rate of 600Hz. One patient had dysembryoplastic neuroepithelial tumor (DNT) and three patients had focal cortical dysplasia (FCD). Aberrant areas were superimposed, to reconstruct 3D MRI images, and illustrated as moving images.

Results: In three patients, short-time Fourier transform (STFT) analyses of MEG showed rhythmic activities just above the lesion with FCD and in the vicinity of DNT. In one patient with FCD in the medial temporal lobe, rhythmic activity appeared in the ipsilateral frontal lobe and temporal lateral aspect. These findings correlate well with the results obtained by intraoperative electrocorticography. After the surgery, three patients were relieved of their seizures, and the area of rhythmic MEG activity disappeared or become smaller. One patient had residual rhythmic MEG activity, and she suffered from seizure relapse.

Conclusion: Time-frequency analyses using STFT successfully depicted MEG rhythmic fast activity, and would provide valuable information for pre- and post-surgical evaluations to define surgical strategies for patients with epilepsy.
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http://dx.doi.org/10.1016/j.eplepsyres.2009.10.002DOI Listing
February 2010

[(11)C]flumazenil positron emission tomography analyses of brain gamma-aminobutyric acid type A receptors in Angelman syndrome.

J Pediatr 2008 Apr 5;152(4):546-9, 549.e1-3. Epub 2007 Nov 5.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan.

Objective: To evaluate the role of the gamma-aminobutyric acid type A (GABA(A)) receptor in Angelman syndrome (AS).

Study Design: We performed [(11)C]flumazenil positron emission tomography (PET) and examined GABA(A) receptor expression in 7 patients with AS of various genotypes (5 with the deletion, 1 with an imprinting defect [ID], and 1 with a UBE3A mutation) and 4 normal control healthy volunteers.

Results: Relative to the control subjects, the [(11)C]flumazenil binding potentials (BPs) were significantly higher in the cerebral cortex and cerebellum in the 5 patients with the deletion and in the 1 patient with a UBE3A mutation, and were less frequently or barely increased in adult patients with the deletion and in the patient with IDs.

Conclusions: Total GABA(A) receptor expression was increased in patients with AS with various genotypes. We suggest that a developmental dysregulation of the GABA(A) receptor subunits occurs in patients with AS.
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http://dx.doi.org/10.1016/j.jpeds.2007.08.038DOI Listing
April 2008

Aberrant somatosensory-evoked responses imply GABAergic dysfunction in Angelman syndrome.

Neuroimage 2008 Jan 15;39(2):593-9. Epub 2007 Sep 15.

Department of Pediatrics, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan.

A role for gamma-aminobutyric acid (GABA)ergic inhibition in cortical sensory processing is one of the principle concerns of brain research. Angelman syndrome (AS) is thought to be one of the few neurodevelopmental disorders with GABAergic-related genetic involvement. AS results from a functional deficit of the imprinted UBE3A gene, located at 15q11-q13, resulting mainly from a 4-Mb deletion that includes GABA(A) receptor subunit genes. These genes are believed to affect the GABAergic system and modulate the clinical severity of AS. To understand the underlying cortical dysfunction, we have investigated the primary somatosensory-evoked responses in AS patients. Subjects included eleven AS patients with a 15q11-q13 deletion (AS Del), two AS patients without a 15q11-q13 deletion, but with a UBE3A mutation (AS non-Del), six epilepsy patients (non-AS) and eleven normal control subjects. Somatosensory-evoked fields (SEFs) in response to median nerve stimulation were measured by magnetoencephalography. The N1m peak latency in AS Del patients was significantly longer (34.6+/-4.8 ms) than in non-AS patients (19.5+/-1.2 ms, P<0.001) or normal control subjects (18.4+/-1.8 ms, P<0.001). The next component, P1m, was prolonged and ambiguous and was only detected in patients taking clonazepam. In contrast, SEF waveforms of AS non-Del patients were similar to those of control individuals, rather than to AS Del patients. Thus, GABAergic dysfunction in AS Del patients is likely due to hemizygosity of GABA(A) receptor subunit genes, suggesting that GABAergic inhibition plays an important role in synchronous activity of human sensory systems.
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http://dx.doi.org/10.1016/j.neuroimage.2007.09.006DOI Listing
January 2008

Possible involvement of the tip of temporal lobe in Landau-Kleffner syndrome.

Brain Dev 2007 Sep 26;29(8):529-33. Epub 2007 Mar 26.

Department of Pediatrics, Hokkaido University, Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan.

Landau-Kleffner syndrome (LKS) is a childhood disorder of unknown etiology characterized by an acquired aphasia and epilepsy. We have performed comprehensive neurofunctional studies on an 8-year-old girl with typical LKS, with the aim of identifying lesions that may be responsible for her condition. 18F-fluoro-D-glucose (FDG) positron emission computed tomography (PET), 11C-Flumazenil (FMZ) PET, 99mTc-hexamethylpropyleneamine oxime single photon emission computed tomography (SPECT) and magnetoencephalography were performed before and after changes to the patient's medication led to a clinical improvement. Interictal SPECT showed hypoperfusion in the left frontal, left temporal, and left occipital lobes. 18F-FDG PET demonstrated a decrease in glucose metabolism medially in both temporal lobes and superiorly in the left temporal lobe. 11C-FMZ PET revealed a deficit in benzodiazepine receptor binding at the tip of the left temporal lobe. Magnetoencephalography demonstrated equivalent current dipoles located superiorly in the left temporal lobe. Our results suggest that the tip of the left temporal lobe plays an important role in the pathogenesis of LKS in our patient.
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http://dx.doi.org/10.1016/j.braindev.2007.01.011DOI Listing
September 2007

Application of magnetoencephalography in epilepsy patients with widespread spike or slow-wave activity.

Epilepsia 2005 Aug;46(8):1264-72

MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, Massachusetts, USA.

Purpose: To examine whether magnetoencephalography (MEG) can be used to determine patterns of brain activity underlying widespread paroxysms of epilepsy patients, thereby extending the applicability of MEG to a larger population of epilepsy patients.

Methods: We studied two children with symptomatic localization-related epilepsy. Case 1 had widespread spikes in EEG with an operation scar from a resection of a brain tumor; Case 2 had hemispheric slow-wave activity in EEG with sensory auras. MEG was collected with a 204-channel helmet-shaped sensor array. Dynamic statistical parametric maps (dSPMs) were constructed to estimate the cortical distribution of interictal discharges for these patients. Equivalent current dipoles (ECDs) also were calculated for comparison with the results of dSPM.

Results: In case 1 with widespread spikes, dSPM presented the major activity at the vicinity of the operation scar in the left frontal lobe at the peak of the spikes, and some activities were detected in the left temporal lobe just before the peak in some spikes. In case 2 with hemispheric slow waves, the most active area was located in the left parietal lobe, and additional activity was seen at the ipsilateral temporal and frontal lobes in dSPM. The source estimates correlated well with the ictal manifestation and interictal single-photon emission computed tomography (SPECT) findings for this patient. In comparison with the results of ECDs, ECDs could not express a prior activity at the left temporal lobe in case 1 and did not model well the MEG data in case 2.

Conclusions: We suggest that by means of dSPM, MEG is useful for presurgical evaluation of patients, not only with localized epileptiform activity, but also with widespread spikes or slow waves, because it requires no selections of channels and no time-point selection.
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http://dx.doi.org/10.1111/j.1528-1167.2005.65504.xDOI Listing
August 2005

Dynamic statistical parametric mapping for analyzing the magnetoencephalographic epileptiform activity in patients with epilepsy.

J Child Neurol 2005 Apr;20(4):363-9

MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA, USA.

Our current purpose is to evaluate the applicability of dynamic statistical parametric mapping, a novel method for localizing epileptiform activity recorded with magnetoencephalography in patients with epilepsy. We report four pediatric patients with focal epilepsies. Magnetoencephalographic data were collected with a 306-channel whole-head helmet-shaped sensor array. We calculated equivalent current dipoles and dynamic statistical parametric mapping movies of the interictal epileptiform discharges that were based in the minimum-L2 norm estimate, minimizing the square sum of the dipole element amplitudes. The dynamic statistical parametric mapping analysis of interictal epileptiform discharges can demonstrate the rapid change and propagation of interical epileptiform discharges. According to these findings, specific epileptogenic lesion-focal cortical dysplasia could be found and patients could be operated on successfully. The presurgical analysis of interictal epileptiform discharges using dynamic statistical parametric mapping seems to be promising in patients with a possible underlying focal cortical dysplasia and might help to guide the placement of invasive electrodes.
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http://dx.doi.org/10.1177/08830738050200041601DOI Listing
April 2005